Seeking to reduce head contact, NFL mandates use of Guardian Cap helmet for early portion of training camp - ESPN
Football helmets don't protect against concussion — and we're not sure what does
NFL hopes to reduce head injuries with helmet experiment
First QB helmet designed to help reduce concussions approved
Riddell launches Axiom, latest helmet to combat concussions
Guardian Cap used by football teams to protect against head injury – The Denver Post
NFL safety: How VICIS' position-specific helmets have become all the rage - The Athletic
New Helmet Technology Aimed to Make Football and Other Sports Safer
See the new football helmet that got funding from the NFL
NFL Football Brain Injuries Helmet Research & Preventing Concussions
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